Watts Angle (WA) and Axis Angle (AA)
Axis Angle - the angle of the event around the limb of the moon,measured eastward from the moon's north pole. Essential forreappearance, as it locates the event with reference to lunar features.To use, mark a map of the moon around the circumference at 10 degintervals, starting at the north pole. Mare Crisium is at about 300deg.
[Note - the so-called Watts Angle differs from the Axis Angle by 0.21deg. The term Watts Angle is limited to the context of accessing theWatts Charts. In all other situations, the term Axis Angle ispreferred.]